Update on Gypsum Application and Rain
I’m regrouping a bit from my previous e-mails on applying additional calcium. I discussed this with a colleague and friend that has conducted research on this and has data from an irrigation study over 2 years with a considerable amount of anecdotal evidence as well. With the exception of a heavy rainfall event that washed soil from the pegging zone (when peanuts are small) there is no need to apply additional gypsum (unless it simply helps someone sleep at night, and then they should only consider the half rate.)
In a wet year, not only is there calcium from the gypsum but there is also a considerable amount of calcium from lime that most likely is in the soil-water solution available for movement into pegs and pods (this would not be the case in a dry year).
In table 3-20 (2014 Peanut Information) you will see that on average the yield increase from a 1X rate over the 1/2x rate is about 80 pounds per acre. The big jump came from the 1/2X rate over the no-gypsum control at 540 pounds per acre. These studies were conducted in relatively normal years (as far as I can remember) and would have been with varieties like Perry, CHAMPS, NC 12C, etc. Based on the discussion from yesterday, the data showing only a minor increase of 1X over 1/2X , planting a lot of Bailey and which is relatively small-seeded Virginia type, and the assumption that in wet years a portion of calcium from lime is most likely in the soil solution, there seems to be no need to reapply gypsum. My assumption is that if you put out a 1X rate and lost half of it you still have enough remaining to do the bulk of the work needed to increase yield and grades.
I don’t think the storm dropped as much rain has we might have expected. Based on the CRONOS system in NC, Lewiston-Woodville received just under 3 inches (and they needed it) and Whiteville had about 0.8 inches. Certainly further east like Craven, Pitt, etc. could have gotten more.
Hope this helps. I am a “life-long-learner” and occasionally can remember what I have learned. Thanks for the patience, and thanks for the information Jay!
Article first appeared as North Carolina Peanut Note (PNNC-2014-088)